Method of setting etching parameters and system therefor

ABSTRACT

The present invention relates to a system that automatically calculates optimal etching parameters in order to perform desired etching in an etching process in semiconductor manufacturing. A model representing etching parameters and an etching performance quantitative value at the time when etching is performed with the etching parameters is prepared in advance, and when desired etching is performed, optimal etching parameters are calculated from the model.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application relates to and claims priority from Japanese Patent Application No. 2003-198844, filed on Jul. 18, 2003, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of setting optimal etching parameters in a semiconductor manufacturing process and a system therefor. More specifically, the present invention relates to a system that picks up an image of a pattern formed on a wafer, represents workmanship of the pattern quantitatively, performs etching parameter correction for reducing an amount of deviation between a quantitative value of the workmanship and a target etching pattern, and realizes setting for optimal etching parameters, and a performance evaluation system that evaluates performance of etching.

2. Description of the Related Art

A conventional method of setting etching parameters (a gas flowrate, a pressure, a voltage, electric power, temperature, time, etc.) for an etching process in semiconductor manufacturing will be explained with reference to FIG. 2. In the etching process, in order to obtain desired etching performance, it is necessary to set plural etching parameters to optimal values.

Instep 201, in order to perform desired etching, a person determines initial values of etching parameters, which are suitable for a quality of material of an etching object and an etching shape, with a help of experiences in the past and intuition on the basis of characteristics, which have been obtained through experiments, concerning the quality of material of the etching object and characteristics of an etching apparatus being used.

In step 202, the person performs etching with the etching parameters determined in step 201. In step 203, the person observes a pattern on a wafer, which is formed by the etching, with a scanning electron microscope (SEM) or the like to measure the etching pattern. In step 204, the person judges manually whether desired etching performance is obtained on the basis of a measurement value obtained in step 203. If it can be judged that a result of the etching is satisfactory, the person determines etching parameters.

If it is judged that the result of the etching is unsatisfactory, in step 205, the person performs correction for the etching parameters, which brings etching performance close to the desired etching performance, on the basis of experiences in the past. Then, the person returns to step 202 and performs etching again with etching parameters set anew.

According the method described above, the person determines etching parameters most suitable for obtaining the desired etching performance.

In the above-mentioned conventional technique, the person determines initial values and corrected values of etching parameters according to experiences and intuition to derive optimal etching parameters. However, such manual setting for etching parameters is inefficient because the manual setting takes time until optimal setting for etching parameters is obtained. In addition, it is possible that set values contain individual differences.

SUMMARY OF THE INVENTION

Thus, the present invention has been devised in view of these problems, and it is an object of the present invention to provide a method of setting optimal etching parameters for performing desired etching and a system therefor.

The present invention provides a method of setting parameters for etching, which includes: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer to judge workmanship of the pattern; presenting a result of judging the workmanship to a user; calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship; and sending the calculated corrected value to the etching apparatus, and a system for the method.

In addition, the present invention provides a method of setting parameters for etching, which includes: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer to extract a characteristic amount of the pattern; comparing the extracted characteristic amount of the pattern with data set in advance to judge workmanship of the pattern; presenting a result of judging the workmanship to a user; and calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship, and a system for the method.

These and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a diagram showing a system for setting optimal etching parameters according to the present invention;

FIG. 2 is a diagram showing a conventional method;

FIG. 3 is a conceptual diagram showing the system for setting optimal etching parameters;

FIGS. 4A and 4B are diagrams showing examples of characteristics of etching performance;

FIG. 5 is a flow diagram of processing for deriving an etching performance quantitative value;

FIG. 6 is a conceptual diagram showing a system for setting optimal etching parameters in a mass production process;

FIG. 7 is a diagram showing a structure of a scanning electron microscope (SEM);

FIG. 8 is a diagram showing an example of GUI display of an etching performance quantitative value;

FIG. 9 is a flow diagram of processing for creating an optimal parameter calculation model;

FIG. 10 is a conceptual diagram showing a method of changing parameters;

FIG. 11 is a flow diagram of processing for setting optimal etching parameters;

FIG. 12 is a flow diagram of correction for the optimal parameter calculation model in a mass production process; and

FIG. 13 is a diagram showing a structure of a scanning electron microscope (SEM) that is capable of acquiring a tilt image.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be hereinafter explained with reference to the accompanying drawings.

First Embodiment

Outline

FIG. 1 shows a system configuration for automating parameter setting at the time of an etching process in semiconductor manufacturing in accordance with an embodiment of the present invention. This system includes an etching apparatus 1, a scanning electron microscope (SEM) 2 that picks up images of an etching pattern, and a computer 3 including a processing unit 4, which performs image processing and optimal etching parameter derivation processing, and a storage 5, which saves etching pattern images, etching parameters, and the like. The respective components are connected by a bus 6.

FIG. 3 shows a flow of processing of this system. First, in step 301, a modeled relation between various image characteristic amounts, which are derived from electron beam images of etching patterns that are formed when etching is performed by changing etching parameters (a gas flow rate, a pressure, wafer temperature, a coil magnetic field, etc.) in various ways, and the etching parameters are prepared in a preliminary experiment (hereinafter referred to as an optimal parameter calculation model). In step 302, an etching target value for an etching pattern to be formed by etching is set. In step 303, initial etching parameters are set using the optimal parameter calculation model prepared in advance. In step 304, etching is performed on the basis of the etching parameters set in step 303. In step 305, an image of an etching pattern on a wafer formed by the etching is picked up by a scanning electron microscope (SEM) or the like. In step 306, a performance value of the etching is calculated by image processing with respect to the image obtained in step 305. In step 307, it is judged whether the obtained etching performance value satisfies the etching target value. If the etching performance value satisfies the etching target value, an etching recipe at that point is set as optimal etching parameters for the etching target value. If the etching performance value does not satisfy the etching target value, in step 308, an etching parameter corrected value for bringing an etching result close to the target etching value is calculated on the basis of the optimal parameter calculation model. In step 309, optimal etching parameters are set on the basis of the calculated corrected value. Then, etching is performed again with an etching recipe set anew (the processing is returned to step 304).

Details of the respective steps will be hereinafter explained.

(1) Derivation of an Optimal Parameter Calculation Model (Step 301 in FIG. 3).

A method of deriving an optimal parameter calculation model will be explained. In this embodiment, a response surface model, which is generally used for statistical processing, is used as a modeling method for an optimal parameter calculation model. FIG. 9 is a diagram showing processing to establishing an optimal parameter calculation model. First, it is assumed that items of a target etching performance quantitative value are A, B, and C, and items of etching parameters to be set in an etching apparatus are a, b, c, d, e, and f. A, B, and C are, for example, line edge roughness, a line width, a contact hole diameter, a hole roundness, and a characteristic amount of a contact hole bottom pattern, and a, b, c, d, e, and f are, for example, a gas flow rate, a pressure, a voltage, electric power, temperature, and time.

First, in step 901, an evaluation experiment using, for example, a Taguchi method is performed to find parameters, which affect in-plane evenness in an etching process, among the etching parameters. In step 902, the etching parameters affecting in-plane evenness are excluded from controllable parameters (e.g., d, e, and f). These parameters are always fixed as fixed etching parameters, whereby evenness on a wafer is prevented from being ruined. In step 903, experiment data necessary for the derivation of an optimal parameter calculation model (experiment data with the etching parameters a, b, and c as inputs and the etching performance quantitative values A, B, and C as outputs) is acquired using, for example, an experimental design method. In step 904, an optimal parameter calculation model using a response curve is created. An optimal parameter calculation model to be generated by the response surface method is a multidimensional model with the items of the target etching performance quantitative value A, B, C as inputs and the etching parameters a, b, and c as outputs.

(2) Setting for an Etching Target Value (Step 302 in FIG. 3)

A desired etching target value is set. For example, in the case in which an etching pattern is a contact hole, a hole diameter, hole roundness, a white band portion width in an image photographed by a scanning electron microscope, roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, an inclination angle of a hole wall, and the like are target values.

(3) Etching Parameter Setting Using the Optimal Parameter Calculation Model

The etching target value is inputted to the optimal parameter calculation model prepared in advance in step 301 to calculate initial etching parameters.

(4) Acquisition of an SEM Image (step 305 in FIG. 3)

An image of an etching pattern is picked up by a scanning electron microscope (SEM). FIG. 7 is a block diagram showing a structure of the scanning electron microscope (SEM) that observes an object formed by etching on a wafer (contact hole, etc.). In FIG. 7, a primary electron beam 702 emitted from an electron gun 701 of an electro-optic system 700 is focused and irradiated on a wafer 710 placed on a stage 711 through a condensing lens 703, a beam deflector 704, an E×B deflector 705, and an object lens 706. When the electron beam is irradiated, a secondary electron is generated from the wafer 710.

The secondary electron generated from the wafer 710 is deflected by the E×B deflector 705 and detected by a secondary electron detector 707. A two-dimensional electron beam image is obtained by two-dimensional scanning of the electron beam by the beam deflector 704 or repeated scanning in an X direction of the electron beam by the beam deflector and detection of electrons that are generated from the wafer 710 in synchronization with continuous movement in a Y direction of the wafer 710 by a stage 711.

A signal detected by the secondary electron detector 707 is converted into a digital signal by an A/D converter 708 and sent to an image processing unit 720. The image processing unit 720 has an image memory for temporarily storing a digital image and a CPU that performs calculation for a line profile and a characteristic amount from an image on the image memory. In addition, the image processing unit 720 has a storage medium 721 for saving the characteristic amount calculated from a result of image processing as a database and a display 722 that displays the image and the processing result.

In this embodiment, prior to carrying in a product wafer, a correspondence model of etching parameters, which are adjusted to obtain a desired etching pattern, and a characteristic amount, which is desired from an electron image of an etching pattern that is formed when the etching parameters are changed, (hereinafter referred to as an optimal parameter calculation model) is derived by a preliminary experiment and saved in a storage 5 b shown in FIG. 1.

As the scanning electron microscope to be used, a scanning electron microscope that picks up a tilt image may be used in addition to the one that picks up a top-down view image. As means for picking up a tilt image, a system for inclining a table 711 on which the wafer 710 is mounted or a system for controlling a trajectory of a primary electron beam with an electro-optic system of the scanning electron microscope (SEM) to make the primary electron beam incident on a wafer surface from an inclined direction maybe adopted. In both the systems, a tilt angle (an inclination angle of a primary electron beam with respect to a normal direction of the wafer surface) is set between 0° to about 15° to obtain a tilt image.

FIG. 13 shows an example of an SEM structure for obtaining a tilt image by inclining a table (tilt stage). The SEM structure shown in FIG. 13 is substantially the same as that shown in FIG. 7. A primary electron beam 1302 emitted from an electron gun 1301 of an electro-optic system 1300 is focused and irradiated on a wafer 1301 placed on a stage 1311 through a condensing lens 1303, a beam deflector 1304, an E×B deflector 1305, and an object lens 1306. A secondary electron generated from the wafer 1310 is deflected by the E×B deflector 1305, detected by a secondary electron detector 1307, converted into a digital signal by an A/D converter 1308, and sent to an image processing unit 1320. The image processing unit 1320 has an image memory for temporarily storing a digital image and a CPU that performs calculation for a line profile and a characteristic amount from an image on the image memory. In addition, the image processing unit 1320 has a storage medium 1321 for saving the characteristic amount calculated from a result of image processing as a database and a display 1322 that displays the image and the processing result.

Here, the structure show in FIG. 13 is different from the structure shown in FIG. 7 in that the table 1311 has a tilt function and it is possible to set an inclination angle of a primary electron beam with respect to a normal direction of a surface of the wafer 1311 to obtain a tilt image. The image processing unit 1320 calculates a height of a pattern according to a principle of stereo graphic view from a tilt image and a top-down view image obtained by the SEM with such a structure, and information on a three-dimensional structure (a pattern height, a taper angle, etc.) is used as a characteristic amount of an etching pattern. Consequently, more detailed setting for an etching target is performed.

(5) Performance Quantization (Step 306 in FIG. 3)

As an example of a characteristic amount derived from an electron beam image of an etching pattern (a line patter, a hole pattern, etc.), an etching performance quantitative value is proposed. The etching performance quantitative value is obtained by picking up an image of an object generated by etching with an SEM and applying image processing to the picked-up image. For example, in the case in which an object of formation on a wafer to be observed is a line pattern, characteristic amounts (a line width 401, line edge roughness 402, a white band width 403, etc.) are represented quantitatively by image processing as shown in FIG. 4A.

In addition, in the case in which an object of formation on a wafer is a hole pattern, characteristic amounts (a hole diameter 410, hole roundness 411, a white band portion width 412, roughness of a white portion contour line 413, roughness of a contact hole bottom pattern 414, etc.) are represented quantitatively by image processing as shown in FIG. 4B. FIG. 5 shows a method of deriving a workmanship quantitative value of a contact hole.

(6) Judgment (Step 307 in FIG. 3)

It is judged using threshold processing or the like whether or not the performance quantitative value calculated in step 306 is within a fixed allowable range with respect to the etching target value set in step 302. In addition, an amount of deviation of an optimal etching parameter from a target value is calculated.

(7) Etching Parameter Correction Using a Minimum Parameter Calculation Model

FIG. 10 a conceptual diagram showing how optimal etching parameters are calculated from an amount of deviation of an etching performance quantitative value from a target value. In the figure, in order to facilitate explanation, a three-dimensional model, in which only etching parameter elements a and b relate to an etching performance quantitative value A, is assumed. In the case in which the etching performance value A does not satisfy a target value, it is assumed from a shape of a model surface how the etching parameters (the parameters a and b) should be change from etching parameter positions on the model at that point to bring a result of etching close to a target etching performance value. The etching parameters are changed finely in a direction of the change and use them as next etching parameters.

In FIG. 11, an optimal etching parameter determination method is shown which uses an optimal parameter calculation model at the time when the etching performance quantitative values are A, B, and C in the case in which etching parameters are a, b, c, d, e, and f. In this figure, a three-dimensional model, in which only the etching parameters a and b, the etching parameters b and c, and the etching parameters c and a relate to the etching performance quantitative values (which is indicated as “etching performance” in the figure) A, B, and C, respectively, is assumed. Actually, as described before, an optimal parameter calculation model, which is generated according to the response surface method, is a multidimensional model with the items of the target etching performance quantitative value A, B, and C as inputs and the etching parameters a, b, and c as outputs.

As described above, etching parameters most suitable for realizing desired etching are derived on the basis of the optimal parameter calculation model. In the above-mentioned method, etching parameters are changed finely. However, etching parameters leading to an optimal etching performance value, which are calculated from the model, may be used as the next etching parameters directly.

(8) GUI (Step 306 and Step 307 in FIG. 3)

An etching performance quantitative value after etching calculated in step 306 is displayed on a GUI shown in FIG. 8. An inputted image 801 and a result of performance quantization area extraction 802 are displayed in an upper part of the screen and a result of judgment on quality of etching and performance quantitative values (hole diameter, white band portion thickness, white band portion contour roughness, hole bottom pattern roughness, etc.) are displayed in a lower part of the screen (803) such that a user can easily understand a state of etching performance.

In addition, if a result of the quality judgment for etching calculated in step 307 indicates defectiveness, a result of judging a cause of the defectiveness (etching stop, occurrence of deposition, etc.) is also displayed (804).

This embodiment is a system that automatically derives etching parameters most suitable for realizing target etching as in the above-mentioned method.

Second Embodiment

System for Calculating Optimal Etching Parameters at the Time of Mass Production

This embodiment is an example concerning optimization for etching parameters in an etching process at the time of mass production in semiconductor manufacturing. FIG. 6 shows a constitution of this embodiment. When an etching apparatus is continuously operated at the time of mass production in semiconductor manufacturing, with the method of deriving etching parameters described above (first embodiment), desired etching cannot be calculated in some cases due to disturbance such as dirt in the apparatus. Such a situation may be caused because effective values of etching parameters deviate from set values thereof due to dirt in the apparatus. This is equivalent to deviation of axes of etching parameters in an optimal etching parameter calculation model. Thus, in order to control between-lot variation, within-lot variation, and dispersion variation based on variation with time and to carry out accurate device processing, in the case in which a result of measurement of the etching parameters deviates from a target value, axes of etching parameters at the time of creation of an initial calculation model are corrected.

The optimal parameter calculation model is used again after the correction to calculate an optimal recipe from the target value. However, in the case in which values of etching parameters calculated from the corrected model are outside a range of values that can be set by the etching apparatus, an alarm is notified for etching treatment for a second wafer to prevent the etching treatment from being performed. Consequently, when abnormality has occurred in the apparatus, a large number of defects can be prevented from being caused. In addition, this alarm can also be used for judgment on execution of maintenance processing called total cleaning. According to the above-mentioned method, optimal etching parameters are set in an etching process at the time of mass production.

A processing flow shown in FIG. 6 will be explained. First, in step 601, an etching target value for an etching pattern to be formed by etching is set. In step 602, initial etching parameters are set. In step 603, etching is performed on the basis of the etching parameters set in step 602. In step 604, an image of an etching pattern on a wafer formed by the etching is picked up by a scanning electron microscope (SEM) or the like. In step 605, a performance value of the etching is calculated by image processing with respect to the image obtained in step 604. In step 606, it is judged whether the obtained etching performance value satisfies the etching target value set in step 601. Here, if the etching performance value satisfies the etching target value, wafers are subjected to etching treatment one after another without changing the etching parameters at that point.

If it is judged in step 606 that the etching performance value does not satisfy the etching target value, in step 608, an etching parameter corrected value for bringing an etching result close to the target etching value is calculated, and a result of the calculation is fed back to step 602 for setting optimal etching parameters to set optimal etching parameters. Then, etching is performed again with an etching recipe based on the etching parameters set anew.

The present invention makes it possible to calculate optimal etching parameters for obtaining desired etching performance in an etching process in semiconductor manufacturing. In addition, the present invention makes it possible to control influence of disturbance due to continuous operation of an apparatus to continue etching with optimal parameters at the time of mass production in an etching process.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefor to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 

1. A system for setting parameters for etching, comprising: an electron beam image acquiring unit that acquires an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; a unit that processes the electron beam image of the pattern formed on the surface of the wafer, which is obtained by the electron beam image acquiring unit, and judges workmanship of the pattern; a unit that presents a result of judgment by the workmanship judging unit to a user; a unit that calculates corrected values of etching parameters for the etching apparatus on the basis of the result of judgment by the workmanship judging unit; and a transmitting unit that transmits the corrected values calculated by the calculating unit to the etching apparatus.
 2. A system for setting parameters for etching according to claim 1, wherein the electron beam image acquiring unit includes: an electron beam irradiating unit that irradiates a converged electron beam on the surface of the wafer and scans the surface; and a detecting unit that detects secondary charged particles that are generated from the surface of the wafer as the electron beam irradiating unit irradiates an electron beam on the surface and scans the surface, and the electron beam irradiating unit can change an incident angle of the converged electron beam with respect to the pattern on the surface of the wafer in a range from 0° to 15° with respect to a normal direction of the surface of the wafer.
 3. A system for setting parameters for etching according to claim 1, wherein the unit that judges workmanship of the pattern includes: a dimension extracting unit that processes the image of the pattern to calculate dimensions of plural portions of the pattern as workmanship of the pattern; and a comparing unit that compares the dimensions of the plural portions of the pattern calculated in the dimension extracting unit with target values set in advance.
 4. A system for setting parameters for etching according to claim 1, wherein the unit that calculates corrected values of etching parameters for the etching apparatus includes; a storing unit that stores a model representing a relation between information on workmanship of a pattern and etching parameters; and a corrected value calculating unit that compares the information on workmanship of the pattern judged by the workmanship judging unit and the model stored in the storing unit to calculate corrected values of the etching parameters.
 5. A system for setting parameters for etching according to claim 1, wherein, in the case in which the pattern is a contact hole, the unit that judges workmanship of a pattern processes an image of the pattern to calculate any one of a hole diameter, hole roundness, a white band portion width, roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, and an inclination angle of a hole wall portion as a characteristic amount of the pattern, and judges workmanship of the pattern on the basis of the calculated characteristic amount.
 6. A system for setting parameters for etching according to claim 1, wherein, in the case in which the pattern is a line pattern, the unit that judges workmanship of a pattern calculates any one of a line width, a white band portion width in an image photographed by a scanning electron microscope, roughness of a white band portion contour, and an inclination angle of a wall portion as a characteristic amount of the pattern and judges workmanship of the pattern on the basis of the calculated characteristic amount.
 7. A system for setting parameters for etching, comprising: an electron beam image acquiring unit that acquires an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; a characteristic amount extracting unit that processing the electron beam image of the pattern formed on the surface of the wafer, which is obtained by the electron beam image acquiring unit, and extracts a characteristic amount of the pattern; a unit that judges performance of acquiring information on a three-dimensional structure with the characteristic amount extracting unit; a unit that presents a result of judgment by the performance judging unit to a user; and a unit that calculates corrected values for etching parameters for the etching apparatus on the basis of a result of judgment by the performance judging unit.
 8. A system for setting parameters for etching according to claim 7, wherein the electron beam image acquiring unit includes: an electron beam irradiating unit that irradiates a converged electron beam on the surface of the wafer and scans the surface; and a detecting unit that detects secondary charged particles that are generated from the surface of the wafer as the electron beam irradiating unit irradiates an electron beam on the surface and scans the surface, the electron beam irradiating unit can change an incident angle of the converged electron beam with respect to the pattern on the surface of the wafer in a range from 0° to 15° with respect to a normal direction of the surface of the wafer.
 9. A system for setting parameters for etching according to claim 7, wherein, in the case in which the pattern is a contact hole, the characteristic amount extracting unit calculates any one of a hole diameter, hole roundness, a white band portion width, roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, and an inclination angle of a hole wall portion as a characteristic amount of the pattern.
 10. A system for setting parameters for etching according to claim 7, wherein, in the case in which the pattern is a line pattern, the characteristic amount extracting unit calculates any one of a line width, a white band portion width in an image photographed by a scanning electron microscope, roughness of a white band portion contour, and an inclination angle of a wall portion as a characteristic amount of the pattern and judges workmanship of the pattern on the basis of the calculated characteristic amount.
 11. A system for setting parameters for etching according to claim 7, wherein the unit that calculates corrected values of etching parameters for the etching apparatus includes; a storing unit that stores a model representing a relation between information on workmanship of a pattern and etching parameters; and a corrected value calculating unit that compares the information on workmanship of the pattern judged by the performance judging unit and the model stored in the storing unit to calculate corrected values of the etching parameters.
 12. A system for setting parameters for etching according to claim 7, further,comprising a transmitting unit that transmits the corrected values calculated by the corrected value calculating unit to the etching apparatus.
 13. A method of setting parameters for etching, comprising the steps of: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer and judging workmanship of the pattern; presenting a result of judging the workmanship to a user; calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship; and transmitting the calculated corrected values to the etching apparatus.
 14. A method of setting parameters for etching according to claim 13, wherein, in the step of acquiring an electron beam image, a converged electron beam is irradiated on the surface of the wafer at an incident angle of a range between 0° to 15° with respect to a normal direction of the surface of the wafer to scan the surface of the wafer.
 15. A method of setting parameters for etching according to claim 13, wherein, in the step of judging workmanship of the pattern, in the case in which the pattern is a contact hole, an image of the pattern is processed, any one of a hole diameter, hole roundness, a white band portion width, roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, and an inclination angle of a hole wall portion is calculated as a characteristic amount of the pattern, and workmanship of the pattern is judged on the basis of the calculated characteristic amount.
 16. A method of setting parameters for etching according to claim 13, wherein, in the step of judging workmanship of the pattern, in the case in which the pattern is a line pattern, any one of a line width, a white band portion width in an image photographed by a scanning electron microscope, roughness of a white band portion contour, and an inclination angle of a wall portion is calculated as a characteristic amount of the pattern and workmanship of the pattern is judged on the basis of the calculated characteristic amount.
 17. A method of setting parameters for etching, comprising the steps of: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron image of the pattern formed on the surface of the wafer and extracting a characteristic amount of the pattern; comparing the extracted characteristic amount of the pattern with data set in advance and judging workmanship of the pattern; presenting a result of judging the workmanship to a user, and calculating corrected values of etching parameters of the etching apparatus on the basis of the result of judging the workmanship.
 18. A method of setting parameters for etching according to claim 17, wherein, in the step of acquiring an electron beam image, a converged electron beam is irradiated on the surface of the wafer at an incident angle of a range between 0° to 15° with respect to a normal direction of the surface of the wafer to scan the surface of the wafer.
 19. A method of setting parameters for etching according to claim 17, wherein, in the step of extracting the characteristic amount, in the case in which the pattern is a contact hole, an image of the pattern is processed, and any one of a hole diameter, hole roundness, a white band portion width, roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, and an inclination angle of a hole wall portion is calculated as a characteristic amount of the pattern.
 20. A method of setting parameters for etching according to claim 17, wherein, in the step of extracting the characteristic amount, in the case in which the pattern is a line pattern, any one of a line width, a white band portion width in an image photographed by a scanning electron microscope, roughness of a white band portion contour, and an inclination angle of a wall portion is calculated as a characteristic amount of the pattern and workmanship of the pattern is judged on the basis of the calculated characteristic amount.
 21. A method of setting parameters for etching according to claim 17, wherein, in the step of calculating corrected values of etching parameters for the etching apparatus, information on workmanship of the pattern judged in the step of judging workmanship is compared with a model representing a relation between information on workmanship of a pattern stored in advance and etching parameters, and corrected values of the etching parameters are calculated.
 22. A method of setting parameters for etching according to claim 17, further comprising the step of sending the calculated corrected values of the etching parameters to the etching apparatus. 